Bed motion mechanism



Aug. 22, 1944. H. E. GOLBER BED MOTION MECHANISM Filed March 16, 1940 8 Sheets-Sheet l QMRhNQwT i m r, m 50 y Q QQ an mi 9% E Q 7 NM Aug. 22, 1944. H. E. GOLBER BED MOTION MECHANISM 8 Sheets-Sheet 2 Filed March 16, 1940 INVENTOR. @fizanifialbe/j 'Aug- H. E. GOLBER BED MOTION MECHANISM Filed March 16, 1940 8 Sheets-Sheet 3 INVENTOR. f ynzaizl 006196;;

v 7 ATTORN 5.

Aug. 22, 1944.

HQ E. GOLBER BED MOTION MECHANISM Filed March 16, 1940 8 Sheets-Sheet 4 INVENT OR.

E Gober; BY

AnfRN sf' Aug. 22, 1944. H. E. GOLBER BED MOTION MECHANISM 8 Sheets-Sheet 5 Filed March 16, 1940 INVENTOR. Hymn/E. Golber, BY 4 A'I'T 1944- H. E. GOLBER 2,356,156

BED MOTION MECHANISM Filed March 1 6, 1940 8 Sheets-Sheet 6 IN VENTOR.

BY E 601681;

ATTORN R E B L O G E BED MOTION MEGHANI SM INVENTOR. 6016621;

8 Sheets-Sheet 7 m G mm m m m mm m QM Aug. 22, 1944. H. E. GOLBER 7 BED MOTION MECHANISM Filed March 16, 1940 8 Sheets-Sheet 8 INVENTOR. Jig/7242725 6 0M761;

- printing presses oi the flat bed, cylinder class,

"its printing stroke;

Patented Aug. 22, 1944 I no norms nacna'iusm v,

' Hyman E. 'Golber, Chicago, Ill., alsignor to Miehle Printing-Press and Manufacturing Company,--: Chicago, IlL, a corporation oilllinois i atpubatjioamarciiie,r1940,scn ijnaszszao 29 Claims.

- My invention pertains toimprovementjslin mechanical movements whereby a uniform, rotary motion or one element shall be converted into a given, linear motion, preferably of non-uniform character, which is to be imparted to another element. a The invention is more particularly adapted for use in .thatclass of machinery where large masses 10 are to, -'be reciprocated at high velocities, and where such masses must be retarded, stopped and accelerated in the opposite direction .within alimited period of time at the end oi each reciprocatory stroke. i

Suchhrequirements are found for instance in where the type bed travels at: uniform speed during actualprinting and is then decelerated and, stopped-and thereupon'reversed to travel in the opposite direction at any desired speed by suitablysacceleratins the bed and then again de- "-celerating'it for its reversal prior to commencing -Whatever the motion required to be transmitted'to the type bed may be, it is extremely important that the change from one speedto another, such as during the reversai'of the bed at the end of each. stroke, shall beeifected with, x the least degree of shock to the parts involved.

In'myU. S. Letters'Patent No. 2,253,270 issued August 19, 1941, for Gears, and thedivisional "Letters Patent No."2,302,942 thereof, issued No- "vember 24; 1942, covering the method of making such gears, I have disclosed. the characteristic features or a novel type oi gear which I preterably term roll-curve gear, and I have also explained the definite steps'involved in themethod -of producing said novel gears.

.lineanmotion that a designer intended'to use for rec procating any gear-driven element. Y B fr'neans of'the method disclosed in said pending" applications, it"is now practical-,'--and 'with comparative ease, to positively produce and-to transmit'with the aid of correlated driving and driven gears any definite motion representednin a designer's speedgraph, such as for instance a 'parabolic'orharmonic motion, or combination thereof, as will become clearly evident.

' 'While the herein described method, and result- (Chit-27). I i 5 r ing gears, may be utiliz edto great advantage in connection with innumerable motion producing mechanism, it isevident that the practical merits of such gears become more, especially evident when applied in" (connection with bed motions or flat-bed, printing presses, where: the inclusion of a parabolic motion is particularly desirable, where marked yariations in thefvelocities' of the masses to bevgreciprocated occur, and, where, the l a d l e n oi ufi m es s t b accomplished at. comparatively f high speeds; fl

It is particularly essential in printing DIC S Ps of the flat-b'edclass, wherethe. masses to lb revciprocated assume considerableproportions, that such masses, shall be underpostive control during their complete cycle'ot reciprocation. Preter- 'abl y, the velocity of the type bed during its return, i. e..non-printing.'stroke, could be speeded up, thereby permitfiin lb more favorable conditions during actual printing and resulting i'n'a'n improved efllciency'of therpre'ss without any'ap- .-m'eciable increase in the'fpress speedit'self.

It is a fact also, thatin thef'past the bed reversing mechanisms in printingv presses were --to a, great degree restricted. to the use ,of these motions which are generatedzzby means of difterent types of crank drives, Insuchcase where "themotion o! the type bed ,duringa portion of its stroke. is intended oiz l qhronizewith a, cylinder rotating at a uniform veloci y, it is evidentfthat crank drives have deilnitevlimitations;

=-"In the realization of the above characteristics f and desirable ieaturea'and theelimination of the disadvantages pointed out herein, much depends mechanism tor the type bed. It is readily "apparent, therefore, that a mechanism which includes a train'oi! gearswherebyany given uniform and non-uniform motion,:or c mbinations mitted to a moving element, is particularly well adapted for use inbed motion -,mechanism.

Accordingly, it is one of the principal objects in the cooperating machineelements and the resultant knocks.

provision of a bed motion-mechanism for printing presses which shall include a trainer rollon the reliability and eflectiveness or the train of" thereof, can be accurately produced and trans- Another salient feature of my invention the l curve sears to provide the desired motion oi :the .type bed-during its-.reciprocatory cycle.

.A viurther important object of the invention is a mechanical movement which will :eiiectively absorb the forces set up :by the reciprocation masses .during ;the operation .of the printing press.

Another obiectand characteristic ieatnre of the present invention .is 1 p oduce a. =bedv motion mechanism whereby the type bed, durin its return i. e. idle stroke, shall be accelerated above the speed given to the bed during :its printing hangers, gates, etc. that require linear displacement during the-runningoiaprinting press.

A iurther iobiejcttci the invention is ,to make possible an operatingspeed oi lilatbedzprinting presses heretofore not attained in presses of this type.

The invention also has ,ior its object to provide a compact, self-.containedidriving unit which limited in parts and capable of transmitting to a typ ed a uts movements while :the :bed is under positive. control.

A further object is the eliminating oi vsl'iock s during the reversal of the .bed at the end of each re i c t n s oke and a any poin wh changes .irom one velocity to another .of the dr v clement occur- I wish to emphasize here that one o f the ideal conditions attainable gby the introduction of my inven n 1 .1% a m ion 2 5 fl -b d nri ting press :is the combination of the desirable ,or

m "i 'elw esc .a n tab i mo on wi h the-desirablegteatures of a harmonic motion. In other words, to (provide in combination with aconstant acceleration motion, a variable accelerationimotion to loin with .a uniform motion.

. Still further objects 0! and advancements made in the ,artby my invention willbecome apbut with aomect the parts removed and taken along line -W -IV otFisure .5:

Figure '1 Ilsa cross section taken'thmugh H8- .ure 6 along the line V-V and'viewed iron the left side oiFigureB:

Figureseand 9-are sectional views taken along lines and VII-VII respectively of i, seen-from the right thereof; and,

Figures 10, 11,12, and .13 are diagrams which diflerent-stages-ot thecycle of reciprocation of .a

type bed.

Because ot the fact-thatthe bed motion mechanism which constitutes the present invention, includes a train of gears which have roll-mam characteristics and thereby represents va practical embodiment of the advantages made :avallable bylthe useof such gears, it isdeemedrduin- ,able for aclearer understanding of my invention, to recite herein at least in partthe essential novel features, pertaining to'this typeoi t me parent from the following specification read in conjunction with the accompanying sheets of drawings.

In .these drawings, which illustrate one pre- Ierred embodimentoi my invention: V

Figure 1 illustrates an original and a modified -q l d spee s aph; an

Figure 2 portrays the pair produced; I

Figure 3 depicts a designer's speedgraph which was developed in accordance with the method described in my Patent No. 2,302,942 granted November 24, 1942, .for Method of Making Gears and which illustrates the curve or a given motion that is to be imparted to a reciprocating element;

Figure 4 shows in iront elevation the general of roll-curve gears have provided in the Iorm of a selfecontained uniton the-outsideofwone of the side frames of a printing press;

Figure 5 is a partial section through thepress taken in front elevation along line III-III of arrangement of the cooperating parts such as I and to the method oi producing them.

It shall bapnderstood, :however, that. .nhiia Figures land 2 oiathadrawingadepict onecharacteristic example 0! combined motionasuch .al

,fOI example parabolic and uniiormmotionpparticu1arly suitable for embodiment in .a mechanism-for reciprocating the typ bedof a printhl' press, any other combinations of motions the 1restorted to, without departi :Iromthe pruciple of the invention.

In the -follow ing description of the istic features inherent in :the roll-curve m and with the introduction of which I amiable to readily produce any desired mechanical .ments such as for examples. parabolic had mo- .tion, which may or ,may not include any harmonic -motion,'for flat-bed printin pr sses. the iollowing definitions should .be kept in mind.

namelyz-acceleration ,is the rate 01' increase a! speed, deceleration is the rate v oi decrease oi speed, displacement is the change of position --wit,h the element of time omitted, speed is the rate .of change of displacement, and b the rate of change of acceleration or ,dQGQlGIP' tion; The term parabolic means a particular kind of non-uniformity where the change is according to thesquare-oi the time.

Let it be assumed that the .problem to be soived is the production of a parbolic bed motion-which includes a pair of correlated driving anddriven spur-gears of which the former is to rotate It a uniform speed and the latter is :to revolve at a speed which, for a portionof the time attic. is variable in order to produce munifo'rm movements.

Accordingly, using a rectilinear-system of ca .ordinates, .a speegraph line is drawn ing the needed sp ed characteristics of driven-gear to be provided, and in Figure 1 such a line is shown partly in full :line and partly in or driven gear to be supplied, the line I'll-1M I portraying a period oi" dwell or non-rota.-

. assure actionoi the gears. and to. aidin' thecutting of the gear-teeth,..and itmay be readily computed,

single point; that is to say, the follower doesnot period represented by the space rotate bathe 'l'iMllI -l-fl; I That straight portion- Ira-m oil'the' line indicates a uniform acceleration oi I rotation of the follower-gear, in other words, 7 a parabolic an "gularedispl'acemen't of the gear around: its axis; the horizontal part' |9'--! I of the' line designates a-'uniform' rotation of'th'e follower or-driven-gear' at theihi'gh'est speed reached at the endi'of the acceleration; and thestrai'ght section. il -411i of the line depicts" a a uniform- --deceleration or arabolic' decrease of angular-displacement of" the rota-ting follower-gear;

In iaawmg such-a speed'gr'aph, any unit of.

length is arbitrarily; chosen toffrepresent the and: drawn; requiring 1 no reference to trigonometriotables;

known unlfonn-rotationsl speed or the: drivinp gear, and the verticalnspeed-ordihates: oi" the 101- lower-gear line or the speedgrapli are oillengths based" upon such unit or leh'gthfthe latter. being) shown in s re 1 as line loo-.1" 1;;

H7 13 'to-bepsrticulan mi time d;

graph the periods o! parabolic angular displacement or the driven-sear are;- not denoted by curved or parabolic lines, butrathe'r by straight inclined or sloping lines l lo-l! and ill--41! in"- dicativ'e of uniform change of speed.

The point- Iil, therefore; depicts a sudden termination of the constantsubstantial-acceleration offthe' follower 'gear' and an abrupt. 'in'sti-- tuition o'f its uniform speed of rotatiomgwhich more-or .le'ssviol'ent transition,., it were allowed tooc'cur would create a -shock :in thevmechanism' with resulting detrimental effect, especiall'yin a machine requiring great accuracy in. the move-- merits of its parts, as, for example, in aprint ing press where registration crpri-nung or eel-- honing of sheets of paper are rism "ml-- 'tan'n'ce.

The point I l represents ra isirnilar but reverse shock-creating condition, 18.1110 the *quiclr' ending of its'uniiorm-speed revolutionrand" the instant establishmentot' its-pe d uniform deceleration" rat a material; rate.

I It'- is to understbod fint her'that' the" area beneath the line III- low B521, or i l 'l lll" represents the angular-displacement or the l'o'h lower-gear, and this, of is; true-or any portions orsuch linos, totalarea MB-IL- 21-410-12' corresponding to,-360. degrees of rotation of the follower-sear.

To avoid such abrupt-or quick changes oi'lrorational the follower or driven'gear, by the at I and 21 ,ai-t' becom'es desirable or necessary' to eliminate these cusps by the sub- 'st'itution or therefor, but in'aarn'uch as,

the areas'below 'such curves must beidealt' withl in "the development ofthe rollcurve fors'thendriven gear, it is otgrea't mportance that thewzcurves chosen shall be-"suchas-(u), to facilitate-or-ioven make possible the ready ascertainment the whole i'partial area below the complete curve or section thereof, and (6) *to -be consonant or compatible with the ninctioning capacity to! available gear-tooth cutting-machines.

I have discovered mama-e best curve toem- "ploy for this purpose, and for-the accomplishment or r the above-stated snd other :bbiectafis a 'parabol'a with its mils:at' flghfiMiElu toj the hb'rinontal base-line, such ome providing s. constant irotatlonalcimpulse towthe follower-sear.

Such parabola should *be preferably relatively large,"rather-thansmall,- in orderto aflordzzsmooth Theparabolaso selectedmay depend somewhat upon the desired requirements. in the finished machine, bearing inmindi that the companion.

driving-gear must: cooperate with. the final -follower. or driven-gear: at these points, and remembering. the facilities available for cutting the gearateeth; etc., but nov difliculty will be experience'dIbyone skilled in the artinproviding such cusp-eliminating parabolas.

Thel parabola. so employed will, in each instance; be' tangent to both of .the lines which it connects; thusassuring no. drastic or undue changes of acceleration of thefollower-gear.

In Figure, 1.. the--speedgraph has been modified to indicate theemployment of parts of two suitableparabolas to remove. the cusps referred to, and; in'such figure, the parabolic lines IS-l! and l 5'l 6have been introduced to take the place of the upper portions or the lines ,III-Il and andathe opposite end portions of the line Inuthe-flnalspeedgraph chart, it is to be remembered thattheordinates of the curverepresent speed,- the areabeneath the curve angulardlsplaoement', and the grades of the curve acceloration or. deceleration, as the case may be i From this new altered speedgraph curve or line .l il.0'-I-l 0 1;3| l'l:5--I 6l-l-80l'08, and in whichtheordinates 14-4" and li-Iili represent the. axes :of the two parabolas, itwill be seen thatthe constant acceleration or parabolic angular-displacement, indicated by the. straight. sloping line lilo-II, is gradually and smoothly modified; as represented by the parabolic line i i--44, so that; although acceleration continues from. II to I 4, itis-no longer constant but rather decreasingandof. atype best described as variable acceleration or harmonic motion, and, at the point i l suchaccele'ration becomes zero and the motion offline follower-gear transformed into a uniformspeedrepresented by thellne H-li.

Again, such uniform rotational speed or the d-riven-or iollowergear-is ended at the point ll *andxdeceleration thereof instituted gradually and smoothlyandthen more or less rapidly increased, as srepresented by the parabola section "-48, and at the point It, such deceleration becomes and continues constant and unvarying until the beginning of thedwell-at the point I80.

:Just :how such sparabolas shall be employed to cut on thecusps in the speedgraph may depend uponsany one. ofeseveral .factors,

In .the present case let us assume that the 'length of 'the uniform speed line l92| is not absolutely-essential-to obtain the required operation of'zthexparts actuated by the driven or follower gear and that .therapidity of acceleration aand deceleration, ,as represented :by .the lines.

JIM-I 9 and 2l--l10. may be slightly changed I without interfering withthe successful operation .irso-thattheiparabola is tangent tothe line I'4--l5 also tangent to the new line ll-l3, the

inclination of line l20-l8 having been changed Just enough so that the area ii--Il--l4-ll0- i30-l I 0, representing angular-displacement oi the driven-gear, in thermal speedgraph, is exactly the same as the original area l20--l0--,i l-- l40--l30|20. i

As is fully shown, this changeoi' inclinationis brought about by shifting the intersection of line l9l20 with the base-line at the point I 20 slightly to the left to point H0 and terminatin the new straight inclined line at the point-i3.

As will be readily understood, another section of parabola i5-l6 is similarly introduced into the diagram to eradicate the cusp atll If it wereessential to maintainthe lengthof line l92 to secure a predetermined period of constant speed of the driven-gear and it were permissible to change theperiod voi, or rate of, acceleration and deceleration, the lines 0-H and 2ll1 0 would be correspondingly modified to permit the introduction of the parabolas.

Or, in some cases, the length of the area lli5-i50i40 under the new curve or line may be increased'in very minor degree to keep the total area under the follower-gear curve the same as in the original speedgraph.

One acquainted. with, and skilled in, this art will encounter no substantial difficulties .in-removing the cusps by the adoption and introduction of the parabolas and at the same time pree serving the required irregular rotation of the follower-gear to be produced. c e

In every instance, the parabola employed has its axis vertical, that is at rightangles tothe base-line, to facilitate mathematical calculation, rather than resorting-to complicated formulieor trigonometric tables.

Actually, in this speedgraph chart of Figure 1, the total angular-displacement of the driving gear should be represented by the area of a rec- Therefore, the dwell part is mechanized, not by roll-curve gears, but-by cams and roller arms.

Moreover, thegear, portions on line "0-" near the point'l l0 andonline l0l00 near the point I00 [are not satisfactory because the gears would unmesh, and so the'cam and roller drive is made to provide also for the disadvantageous lower portions only 01 lines, I i0-i3 and ilf-IIO,

It has been indicated'previously that the cusps are to be removed irom the's'peedgraph and yet two remain at "I I0- and i 00,,these' two occurring, not on the gear-portion, but on the camportion, as dust", stated fabove when, the follower-gear speed-is very l'ow; .yet in some speed'graphs even the speedzero cusps are roundedlout.v

,Nowfor each degree of turn o the driving gear beginning at "zero at the point I00 (lei't hand end or the line), for each corresponding ordinate the total area beneath such curve to thelei't of such ordinate c-represents the total amount of angular displacementor turn of the'driven-ge'ar. In rnathematically determining such areas under each"par'abola,;on' e starts with the axis (TH-l" or l5l50) of the parabola and works backtangle having a length represented by thefull than the length otthe linffli0Q-i30, heverthe-,

the driving-gear or the pair, represent as follows in this particular example:

i00l |0== 29.6388885 degrees |i0-|30= 40.0000000 degrees |30--l40'= 40.0000000 degrees ll-i 50:140.!222230 degrees I50--I00= 40.0000000 degrees |80 -l80= 40,0000000 degrees, M i80-l00= 29.6388885 degrees The illustrated vertical ordinates'of the'fol lower-gear curve of Figure 1 areas "follows and their values show their'proportion 01' the unitspeed ordinate l00---22 of the driving-gear:

As the line portion l00--i00l i0 is a dwell for the driven-gear, point Hit-(Figure 2) on the dotted extension 01' theroll-curve' of the latter would have to be kept at the driving-gear axis, andthis would be quite unsatisfactory for several reasons.

wardly for the parabola l3 -il and forwardly for the parabola l5-l6 as otherwise the computation would perhaps be unduly complex,

For example, "the driven-gear does not begin t'ofr'otate until the driving-gear. has turned 29.6388883 degrees corresponding to the point I i0, and, while'the driving-gear, revolves the next 40 degrees, as representedby that portionof the base line i|0-.-i30, the driven gear must rotate an amount corresponding to the area il0-I3'l30 I which is deterhiined inthis,rx anner Area I I0l3'l30= /2 I Ill-J30) X'( lib-43) Area I l0-l3i30= 40 degrees 1.0062893i Area l|0--i3l30=20.l257862 degrees In this connection it must 'be appreciated that, although the length of line i 3 is greater less the driven-gear is rotatedfla lesser amount during the rotation or the driving-gearthan that of such driving gear, this being due to the, fact that whereas the len gt h'oi' line' I ilk-I30, as we are now' considering it, represents the extentbt rotation'of the driving gear, the area beneath line ll0'- l3 represents the rotation of thdriven-gear during thesa'me period. 3 1 If, however, we werecompa'rii the actual area of the driving-gear rectangle'having a base |Ul30 and a height "IO-f2! with that. 01th: driven-gear triangle li0- l30--l,3 the relative angular-displacements of the two gears during the same period of timelwould be' more obvious.

'The' line l30- l40 depicts a' ,tur'ning ofi,the driving-geanof 40 degrees and, during such rof tation thereof, the drivenfgear will be revolved s, as

.Further, while thevdriving-gea'r turns the next 14031222230 degrees, representedf by the line lit-450,, the driven gear will be-- rotated; 212,4109023 degrees in accordance. with the recturns 20 .125,'l862"degrees..

By this time, the driven-gear has completed its single 360 degree I revolution, and, it ndwells ,or

remains stationary during 'the period thedrivinge: gear, turns-two times 295388885, degrees, that is As Will be .readiiy' understood, the area beneath the straight ;,sloping-;,1ine, I I '-I 3 represents a. uniform acceleration. of the driven-gear, the areabeneath the-section I3 I|-of-the-ver.tical parab- 01a corresponds ,to a constant impulseresulting in a. graduated reduction. or the acceleration,

whereby the irotation; of; the drivenegear, reaches a -unif orm or unvarying -speed, at thepoint 14,. whicl'rv condition persists,= as represented by-the reached, ,whereupon the speedof the drivenegear is decelerated at a gradually increasing. rate,q which, at; thepointli becomes a uniformdecel eration until point I 80 is. reached, where; such deceleration has brought the driven-gear to astandstill, Y

Machines 7 are vassumed ,to be builtoi :rigid ma which itis subjected,

Since in a machine, the inertia forces-are pro-,

such pair-or gears'isvproduced from the speedgraph 0! Figure 12.;

For each degree 01 rotation of the driving-gear,

- as indicated'bythe line IIIII-'-IIIO, the correspond- 59.27.77770 degrees, representedby ,the: combined-= I ingramountotturning of the driven-gear is determined;mathematically in the same general manneras indicated above for the particular points-1 Ifl,l30, I40; I 50; I80, I80, so that for each added degree of turningof the driving-geanfrom its starting point, the total amount of turning of the-driven-gear will be known.

It can be readily demonstrated that with these roll-curvegears, theray'inot radius) :(R. for the driving-gear and -r' for the driven-gear) from theaxis' of the gear aroundwhich it revolves to its .roli-curveata ny,point of the latter is for the drivingegear represented as follows:

R=constant distance between the axes of rotation ofthe two gears (L in this case 16,625

inches) multiplied by, the speedg raph ordinate portionalto the square of ethe machinef-speed.

such bends of its partscreated by such forces proportionalto the square of-the machine-speed times acceleration.

At everyspeedgraph cusp the bodies; would;

have two different bendings corresponding to the different grades'of the lines meeting at the cusp,

and, since it'frequentlyhappens that the,bodies are considerably resilient they, would :bend sum cientlyto cause misplacement of theparts, and,

'at'high speed-would knock-"and result'in defective operation of the mechanism.

or avoidance of cusps-inthespeedgraph ,curve.

The foliowingtablemay beof assistance in (S)v corresponding to the angle or the ray and such;product divided by 1 (one) plus the same speedgraph'ordinate (S) and the equation may be written-thus:

, we and, similarly the equation for the ray of the drivencorfollower gear maybe expressed thus:

1+8 Theroll curve for thedriving-gear may be plotted on alsheet of paper by drawing 360 rays 1 froma common/center "one degree apart and 3 markin on each suchray line the' proper length {thereotas determined by the above-noted formula, and. then by drawing a line through all ohthese points, such'line will represent the rollcurvezfor the driving gear. A .Instead,2howe,ver, of thus plotting such rollcurveby drawing the diverging rays from a com 'mon' center one degree apart, the many successive points'deflning theroll-cu'rve may be plotted by means .0! a system or rectilinear-coordinates. Thedriven-gear roll-curve may be plotted in a similanmanner by drawing the 360 radiating rays equa spacedmndmarking thereon the pointsdetermined by the formula stated above, or theraysmay vary as to the degrees or angle ubetweenthem as determined for each degree of turning otthedrivlng-gear and the marks ,ap-

nates maybe resorted to.

analyzing what happenssto the driven-gearz-at diiterentparts of the speedgraphrchart: 1 v

I havenindicatedhereinthat oneof the outstanding advantages characteristic of a bed mo- Spcedgraph Displacement Speed l Acceleration Impulse Horizontal zero line 0 i 0 0 ,0. Horizontal up iine Changes at um rm rates" Remains constant 0..- 0. Oblique straig Hines. Parabolic. Changesatuniformra Remains constant r- .0. Parabolas Cubic Parab ic Changes at uniiormra Remains constant.

in, Figure 2, the-.drivingegear I3I and1-its.at-.- tendant or mating iollower or dri-ven-gearglfl" are shown in meshed relation, in this, particular or specific: example with a fiiteddistance-of l 16.625inches between their :axes I33 and lurespectively, about which they are .designed to.

mannerin; which. 76; 1

tionwhichimbodies my invention is the fact that the'desirable; or good featuresof a parabolic motionand, the desirable features of .a harmonic motion are retained and combined to join with a uniform motion-,1 whereas the undesirable, or badpoints of a parabolic and of a harmonic motion: are discarded.

Alparabolic.motionprovides a constant, but

smallest possible acceleration for a given stroke, while a harmonic motion has a very gradual change in acceleration when running into, i. e, Joining, a uniform motion. These points are desirable and, therefore, are being retained, whereas the bad points of sudden change in acceleration in a parabolic motion when joining a uniform motion, and that of a high force at the end of a stroke in a harmonic motion, are omitted.

Referring again to the speedgraph depicted in Figure 1, I have indicated zones A, B, C, D, and E. Zone A represents the constant, parabolic acceleration at the beginning of the printing stroke of a type bed for example. v

Zone B corresponds with the harmonicmotion when, near the beginning of the un iform speed of the bed, the acceleration changes at a substantially constant rate, which preferably could be termed variable acceleration.

The uniform speed of the bed, when printing takes place, is represented by zone C.

At the end of such uniform speed, the travel of the bed is decelerated and the motion becomes harmonic, in other words deceleration changes at a substantially constant rate. This phase of the motion is indicated by zone D.

The printing stroke is subsequently ended with a constant deceleration which becomes parabolic and which is depicted by zone E.

In practice, it has been found that, in place of the retained features of a harmonic motion, one could use to great advantage 8. suitable cubic parabola with its origin at the beginning of the uniform speed. 1

The acceleration resulting from such an alternative has a positively constant rate of change and the calculations required are considerably simplified.

In order to make the principle of my invention more readily understood, I will now give a brief explanation of the designers speedgraph depicted in Figure 3 of the attached drawings.

At point I80 the'deceleration'of the bed begins until at the point 220 the bed reverses. The bed continues to travel inthe reversed direction until the point 250' is reached, where the bed assumes its uniform or constant speed for the actual printing period, which extends from point rum-100' ---l in.

If in the speedgraph, depicted in Figure 3, the curve would have been composed so as to include the intersecting broken lines A-B, CD and E-F, then-it would have given rise to the production of roll-curve gears having cusps, such as are disclosed for example in my U. S. Patent No. 2,027,818, Drive mechanism, issued January 14, 1936, which shows a number of different gear segments assembled to form a pair'of gears whereby a given, non-uniform motion to be imparted to a machine element may be approximated. Such cusps are highly objectionable, both from a manufacturing standpoint as well as in the actual operation of a mechanism, because they will produce shocks and knocks unless such gears are made'exceedingly rigid and accurate.

The method which I employ to eliminate such objectionable cusps and therewith avoid any shocks resultant due to such cusps, is described in full details in my pending application for U. 8. Letters Patent identified above, and therefore need not be dealt with here.

Referring now to the practical embodiment of the invention, the printing press to whichmy 'improved mechanical movement is applied byway of example, includes side frames H), -H, a type bed l2 and an impression cylinder l3, see Figure 4. The latter is mounted. for rotation in bear- In that speedgraph the abscissae or horizontal dimension represent the time, usually indegrees of rotation of the driver, the areas between the curve and the horizontal base line represent-the displacement of the follower, the ordinates show angular speed of the follower, and the slope of the curve indicates the rate of acceleration or deceleration.

The curve I00li0l40l80220+250 I00 represents the complete cycle of reciprocation that is to be imparted to a type bed of a printing press. l

The ordinate I0fll00f indicates the maximum speed attained during the printing stroke which speed remains. uniform while the actual printing takes place, whereas the ordinate |80i80' represents the maximum speed reached. during the non-printing i. e. return stroke of the type bed.

It will be seen that at point H0 the slowing down of the type bed begins, it continues until its speed is nil at point I40. There the direction of travel of the bed is reversed to commence its return or idle stroke. From point I40 on the bed is accelerated until it reaches its maximum speed at point I80, where the speed ratio is approximately 2 to 1 as compared with the uniform printing stroke of the bed. I wish it to be understood that this particular ratio is preferred when my invention is applied to the'driving mechanism for a reciprocating type bed, bu'tfthat any desired modification in the speed ratio may be adopted without departing from the scope of this invention.

the impression cylinder rotates continually in one direction and it makes two revolutions .per printing cycle, one during the impression stroke and the other during the return stroke of-the bed. The cylinder is driven fr0mthe main drive shaft 15 through the intermediary of the-driving gear 1 i6 mounted on said shaft and meshing with the cylindergear ii, the source of power being of any suitable kind, such as an. electric motor, not

shown.

illustrated in Figures 4 and 5, on the underside ofthe bed i2 there is provided a rack II which extends longitudinally of the bed and meshes with adriving gear I9 carried by the bed motion shaft 20. This gear is the onlymember acting 'on the bed to-drive it throughout its entire cycle of-reciprocation, having the reciprocating type bed under positive control at all times by always remaining in mesh with the rack.

The inner end of the shaft 20 is supported in a bearing 2i provided in a brace member 22 of the press frame. The other bearing for said shaft is arranged in the side frame ill, through which the shaft extends. Its free end carries two rollcurve gears 23 and 24 and a pair of cam rollers 25 and 26 which rotate freely on studs mounted in discs 25', 26, and 21' rigidly associated with the shaft 20, see Figure 9. The gear 23 meshes intermittently with a'companion roll-curve gear 21, which I term the direct driver and which is secured to the direct shaft 28 mounted for ,rotation in bearings provided in the gear case 30. The gear 24 moves intermittently into'meshing relation with a roll-curve gear 3|, which 1 mounted on the reverse shaft 32 which also has its bearings in the gear case 30.

3| are in meshing relation, as will be more readily understood from the mode ofoperation explained hereinafter.

The main drive shaft i. e. power shaft l5 also carries a gear 38 which meshes with a gear 36 mounted on the shaft 28 which also has rigidly secured thereto a gear 40, see Figure 6, and which latter is in constant meshing relation with a gear 4| keyed to the shaft 32. These latter two gears I preferably term cycle gears to distinguish from roll-curve gears. It will be seen therefore that when the press is in operation, the shafts 26 and 32, and therewith the gears Mand rotate constantly and at the same rate of speed time both of therollers have reached the ends of their respective cam tracks, the roll-curve gear 21 will have advanced sufficiently to move into meshing relation with its correlated gear 23 and the acceleration of the bed will be continued until the uniform type bed velocity is reached, namely at the point 250' of the speedgraph curve shown in Figure 3. The rollers 25 and 26 having in the meantime moved clear of their cams so that the bed will now be under control of the gear 21 only. The period of action-of the node cams 35 and 36 from the time'their cooperating rollers engage, them, to the moment the rollers leave said cams, is represented by the section 2|||' but in opposite directions, and that the shaft 20' will be driven alternately by said shafts 26 and 32, namely in an anti-clockwise direction during the printing stroke of the bed, at which time'the gears 23 and 21 are in mesh, and'in a clockwise direction when thegears 24 and 3| are in mesh during the return stroke of the bed.

The position of the roll-curve gears, node cams and associated rollers as viewed in Figure 4, correspond with the maximum speed of the type bed I2 reached during its return stroke when the cylinderis tripped and no printing takes place, the bed having reached the crest of said stroke and the'roll-curve gears 24 and 3| being in mesh, which position coincides with point I60 of the speedgraph depicted in Figure 3. At this point, of course, the roll-curve gears 23 and 21 are not in mesh and the rollers 25 and 26 are not in rolling contact with their respective cams and 36, the type bed H at that moment has reached the middle of its return stroke.

With a view of rendering more apparent the manner of operation of my novel mechanical drive, I will now turn to Figures 10,11, 12- and 13 which illustrate graphically various positions of the roll-curve gears and associated parts assumed during the cycle of reciprocation of the type bed l2. 'In these figures the radii shown of the gears'involved are terminated atthe pitch lines of the gears, therefore, where the pitch lines touch, the gears are intended to be in mesh and vice versa, and each pair of correlated gears, as well as the pairs of cooperating cams and to 230 of the speedgraph curve depicted in Figure 3.

At the moment when the bed |2 has reached the middle of its uniform stroke, the roll-curve gears and associated cams and rollers shall have assumed the relative positions shown in Figure 11, namely positions when the gears 23 and 21 are in mesh, the gears 24 and 3| are out of mesh, and the cam rollersare not in rolling contact with their respective cams.

Figure 12 illustrates the position of the parts assumed just prior to the end of the printing stroke. The roll-curve gears 23 and 21 are still inmesh, the rollers 25 and,26 have already reached the node cams and 36' respectively. The type bed |2 has almost completed its printing stroke, namely to the left as viewed in this figure, and the impression cylinder is about to be trippedout of printing relation with the form 29.

Assoon as saidrollers have engaged their cams, so that the shaft 20 and therewith the rack pinion l3 and bed i2 are under positive control of said rollers and cams, the gears 21 and 23 will move out of their meshing relation and for a moment 'the' gear 23 will continue to rotate in i an anti-clockwise direction due to the action of the node cam 36 on the roller 26 urging the latter to the left. This movement continues until just prior to reaching the position represented in Figure 13. It will be seen that the roller 26 has proceeded a short distance beyond the high point of the cam 36 and'that due to the engagement of cam 35 with the roller 25 and the conrollers are shade lined alike in order to facilitate a clear understanding of their correlations and actions.

In Figure 10, which depicts the position of the parts at the time whenthe type bed nears the end a of its return stroke and just prior to its reversal and acceleration for the printing stroke, the gears 24- and3l are just moving out of meshand the rollers 25 and 26 are already in rolling contact in the anti-clockwise direction, the shaft 20 will therefore not continue to rotate in a clockwise direction but its direction of rotation will be reversed gradually because the cam 36 during its rotation towards the roller 26 will urge the latter to the left thereby initiating rotation of the shaft 20 in an anti-clockwise direction. By the tinued rotation of said latter cam in .an anticlockwise direction, the latter roller is being urged to the left, swinging the two rollers in a clockwise direction about the axls of shaft 20, thereby maintaining rolling contact between the roller 26 and its cam 36 and in consequence thereof initiatingthe rotation of said rollers and shaft 20 in the clockwise direction and therewith commencing the return stroke of the bed, namely to the right as viewed in Figure 13. Therefore, at the moment the gears 3| and 24 begin to mesh, the latter gear already has commenced to rotate in the direction it will be driven by the reverse drive gear 3|. According to the position shown in Figure 13, said two gears are not yetin mesh but shall be so after a slight further movement of the gear 3| in the direction shown by the arrow. The period of action ot-the node cams during that portion of the cycle of operation just described-, namely from a point considerably prior to the end of the printing stroke to a point considerably after the return stroke of the bed hegins, is represented by the section I30 to I50 of said speedgraph curve. Thereupon the bed shall be under control of the reverse drive gear as shown in Figure 4 until the bed has again reached the-position indicated in Figure 10.

. It is apparent, therefore, that the combination of parts described herein is 'capablenot only of producing the requiredmovements of a mechanical.eleme nt ,,but also will assure a rigid connection between cooperating parts at'all times during the opera'tionof'such element and will 'eIiminateany shooksthat heretoforehave occurred during changes in the velocity of an element, due to forces set up by the reciprocating masses in mechanisms such" as bed motions of type beds in printing presses.

I claim: p v 1. In a bed motion mechanism, the com-bination with a reciprocating bed, of a bed motion gear constituting the only drive applied'to said bed during its 'c'or'nplete reciprocatory cycle, a bed motion shaftcarrying said gear and driving the gear and the bed in opposite directions, two rollcurve gears on said bed'moticn shaft, a second shaft continually rotating at uniform speed in one direction and having a roll-curve gear there-- on for meshingrelation with one of saidtwo rollcurve gears, and a third shaft having" a ran. curve gear thereon for meshing relation with the other one of said gears on said bed motion shaft, said second and third shaft transmitting to I said bed its complete motion.

2. In a bed motion mechanism, the combination with a reciprocating bed, of a bed motion'gear constituting the only drive applied to said bed during its complete reciprocatory cycle, a bed motion shaft carrying said gear and driving the 1 gear and the bed in opposite directions, two rollcurvegears on said bed motion shaft, a'se'cond will be assured between the cooperating parts duringlthechanges of movement of said reciprocating bed.

3. In a bed motion mechanism, the combination with a reciprocating bed of a bed motion gear constituting the only driving member-applied to said bed during its complete reciprocatory cycle. a bed motion shaft carrying said gear and driving the gear and the'bed in opposite directions, two roll-curve gears on said bed motion shaft, 8. second shaft continually rotating at uniform speed in one direction and having a roll-curve gear thereonfor meshin ,rela tion with one of said gears, on the bed motion shaft, and a third shaft continually rotating at uniformspeedin theoppositedirection and having a roll-curve gear thereon for meshing 'rela-.

, tion with the otherone of said gears on the bed motion shaft, said second and third shafts having associated therewith means whereby rigid connection will be assured between the cooper, ating parts during the changes of movement of said reciprocating bed.

4. In a flat-bed printing press, a type bed traveling at a uni-form speed during the printing stroke and having a bed rack and gear for driving the bed, a bed motion shaft for said gear, the-drive for said shaft being composed of two equal, meshing and continuously rotating'cycle gears rotating at auniform speed, one of the cycle gears carrying a roll-curve gear forthe printing stroke and the other carrying a rollcurve gear for the return or idle stroke and a complementary roll-curve sear on the bed moi and including a driving shaft, two driven shafts geared for uniform rotation at the same speed but in opposite directions, a bed motion sh'sft and gear thereon for driving the bed, a pairof roll-curve gears carried by said latter shaft, a roll-curve gear on one of said driven shafts 'complementary to one of said pair of gears for driving the bed during its printing stroke, and

shaft continually rotating atvuniform "speed in one direction and having a rolls-curve gear therea roll-curve gear on the other one of said driven shafts complementary to the other one of said pair of gears for driving the bed during its nonprinting stroke.

6. Inja printing press, a type bedfmechani'sm for imparting reciprocatory movement to said bed and including a driving shaft, two dri'ven pair of rollecurve gears carried by said lattershaft, a roll-curve gear on one of said driven shafts complementary to one of said pair of gears for driving the bed during its printing stroke, and a roll-curve gear on the other one of said driven shafts complementary to the other one of said pair of gears for driving the bedduringits non-printing stroke at a speed different to that imparted to the bed duringits printing stroke.

7. In a printing press, a type bed, mechanism for imparting'reciprocatory movement to said bed and including a driving shaft,two driven shafts geared for uniform rotation at the same speed but in opposite directions, a bed motion-shaft and gear thereon for driving the bed, a pair of roll-curve gears carried by said latter shaft, a roll-curve gear on one of said driven shaftscomplementary to one of said pair of gears for driving the bed during its printing stroke. nd a rollcurve' gear on the other one of said drivenshnftl complementary to the other one of said pair of gears for driving the bed during its non-printing stroke at a speed different to that imparted to the bed during its printing stroke, the ratio of the maximum speed during the return stroke-being substantially two to one tothe constant speed of the bed during its printing stroke.

8. In a printing press, a type bed, mechanism for imparting reciprocator movements to said bed and including a driving shaft, two driven shafts geared for uniform rotation at'the same speed but in opposite directions, a bed-"motion shaft and gear thereon for driving the bed, a pair of roll-curve gears carried by said latter shaft, a roll-curvegear on one of said driven shafts complementary to one of said pair of gears for driving the bed during its printing stroke, a roll-curve gear on the other one of said-driven shafts complementary to the other one of said pair of gears for driving the bed during its nonprinting stroke, a pair of cams on said last mentioned driven shaft, and a pair of cam rollers carried by said bed motion shaft and cooperating with said cams for completing the motion of said bed at the points of reverse.

9. In a printing press, a type bed, mechanism for imparting reciprocatory movement .to said bed and including a driving shaft, two driven shafts geared for uniform rotation at the some speed but in opposite directions, a bed motion shaft and gear thereon for driving the bed, a pair of roll-curve gears carried by saidlatter shaft, 9. roll-curve gear on one of said driven shafts complementary to one of said pair of gears for driving thebed during its printing stroke, a roll-curve gear on the other one of said driven shafts complementary to the other one of said pair of gears for driving the bed during its nonprinting stroke at a speed different to that imparted to the bed during its printing stroke, a pair of cams on said last mentioned driven shaft, and a pair of cam rollers carried by said bed motion shaft and cooperating with said cams for completing the motion of said bed at the points of reverse. 1

10. In a printing press,'a type bed, mechanism for imparting reciprocatory movement to said bed and including a driving shaft, two driven shafts geared for uniform rotation of the same speed but in opposite directions; a bed motion shaft and gear thereon for driving the bed, a pair of roll-curve gears carried'by said latter shaft, a roll-curve gear on one of said driven shafts complementary to one of said pair of gears for driving the bed during its printing stroke, a roll-curve gear on the other one of said driven shafts complementary to the other one of said pair of gears for driving the bed during its nonprinting stroke at a speed different to that imparted to the bed during its printing stroke, a pair of cams on said last mentioned driven shaft, and a pair of cam rollers carried by said bed motion shaft and cooperating with said'cams for completing the motion of said bed at the points of reverse, the ratio of the maximum speed during the return stroke of the bed being substantially two to one to theconstant speed of the bed during its printing stroke.

11. In a bed motion mechanism, the combination with a reciprocating bed, of means including a bed motion shaft and gear thereon which constitute the only driving means applied to said bed during its complete reciprocatory cycle, a direct driving member, means for continually rotating said driving member at uniform speed in one direction, a reverse driving member, means for continually rotating said reverse driving member at uniform speed in the opposite direction, gears on said direct and reverse driving members respectively for controlling motion of the bed motion shaft to thereby drive the bed during the median portions of its reciprocatory cycle, and means including cams on the reverse driving member for controlling motion of the bed motion shaft to thereby reverse the movement of the bed at the ends of its reciprocatory cycle.

12. In a bed motion mechanism, the combination with a reciprocating bed, of means including a bed motionshaft and gear thereon which constitute the only driving means applied to said bed during its complete reciprocatory cycle, a direct driving member for the bed motion shaft, means for continually rotating said driving member at uniform speed in one direction, a reverse driving member for the bed motion shaft, means for continually rotating said reverse driving member at uniform speed in the opposite di-. rection, and means on one of said members for controlling motion of the bed motion shaft to thereby stop and reverse the movement of the bed at the ends of its reciprocatory cycle.

13. In a bed motion mechanism, the combination with a reciprocating type bed, of mechanism for driving the bed during its reciprocatory cycle,

said mechanism including elements constituting the driving means applied to the type bed during its complete sequence of strokes, and actuating means for said elements, organized and operating to impart to the type bed parabolic motion followed by harmonic motion during portions of each stroke of the bed.

14. In a bed motion mechanism, the combination with a reciprocating type bed, of mechanism for driving the bed during its reciprocatory the driving means applied to the type bed during its complete sequence of strokes, and actuating means for said elements, organized and operating to impart to the bed during one stroke thereof parabolic motion, harmonic motion and uniform motion in succession.

16. In a bed motion mechanism, the combina tion with a reciprocatingtype bed, of mechanism for driving the bed during its reciprocatory cycle, elements included in said mechanism which constitute the driving means applied to the type bed during its complete sequence of strokes, and actuating means for said elements for imparting to the type had during one stroke thereof constant acceleration motion, variable acceleration motion and uniform motionin succession, whereby the variable acceleration motion join the constant acceleration motion with the uniform motion.

17. In a bed motion mechanism, the combination with a reciprocating type bed, of mechanism for driving the bed during its reciprocatory cycle, elements included in said mechanism which constitute the driving means applied to the type bed during its complete sequence of strokes, and actuating means for said elements, including rollcurve gears for imparting to said bed during one stroke thereof constant acceleration motion, variable acceleration motion and uniform motion insuccession, whereby the variable acceleration motion joins the constant acceleration motion with the uniform motion.

18. The combination with a reciprocating bed of a printing press, of mechanism for driving said bed during its complete reciprocatory cycle, said mechanism including means for imparting to said bed parabolic-motion, harmonic motion and uniform motion in succession during one stroke, and other means for imparting to said bed parabolic motion and harmonic motion in succession during the other stroke of its reciprocatory cycle.

19. The combination with a reciprocating machine element of mechanism for driving it during its reciprocatory cycle, members included in said mechanism which constitute the driving means- "stroke, and other means for imparting to said machine element parabolic motion and harmonic motion in succession during the other stroke,

the maximum speed during the said other stroke being greater than the maximum speed during the stroke including the uniform motion.

20 The combination with a reciprocating type bed of a printing press, of means for driving said 21. The combination with a reciprocating type bed of a printing press, of means for driving said bed during its complete sequence of strokes, said means comprising mechanism which includes a train of roll-curve gears and associated cam members arranged and operating toimpart to said type bed parabolic motion and harmonic motion during portions of the respective strokes of the bed.

22. The combination with a reciprocating type bed of a printing press, of mechanism for driving the bed, said mechanism imparting to the bed its complete cycle of movement and including two sets of rollecurve gears acting alternately, said sets of roll-curve gears each imparting to the bed parabolic motion and harmonic motion during portions of the respective strokes of the bed.

23. In a bed motion mechanism, the combination with a reciprocating type bed, of mechanism for driving the bed to produce a working stroke in one direction and an idle stroke in a reverse direction, elements included in said mechanism which constitute the driving means applied to the type bed during its complete sequence of strokes, and means for imparting to said bed through the intermediary of said elements parabolic motion during the initial portion of each stroke, followed by harmonic motion, and parabolic motion during the terminal por- -tion of each stroke, preceded by harmonic mosequence of strokes, two alternately acting sets of roll-curve gears and coacting reversing members for imparting to the type bed, through the intermediary of said elements, its complete cycle of movement, each one of said sets of roll-curve gears imparting to the bed during its reciprocatory strokes constant acceleration motion for the initial portion of a stroke followed by variable acceleration motion, and constant deceleration motion for the terminal portion of a stroke preceded by variable deceleration motion.

25. In combination with the reciprocating type bed of a printing press having a working stroke in one direction and a reverse stroke inthe opposite direction, mechanism for driving the bed, elements included in said mechanism which are in constant driving association with said bed and arranged to transmit to the bed its sequence of strokes, two alternately acting sets of roll-curve gears and coacting reversing members for imparting to the typebed, through the intermediary of said elements, its complete cycle of movement, one of said sets of gears driving the bed during the working stroke and the other setdriving it during the reverse stroke, each set of rollcurve gears imparting to the bed during the iniduring the working stroke, additionally imparting to the bed uniform motion for the median portion of the stroke.

2'6. In combination with the reciprocating type bed of a printing press having a working stroke 1 in one direction'and an idle stroke in the opposite direction, mechanism for driving the bed, elements included in said mechanism which are in constant driving association with said bed and arranged to transmit to the bed its sequence of strokes, two alternately acting sets of roll-curve gears and coacting reversing members for imparting to the type bed, through the intermediary of said elements, its complete cycle of movement, one of said sets imparting to the type bed for each working stroke initial, constant acceleration motion followed by variable acceleration motion and then uniform motion, and the other set of roll-curve gears imparting to the type bed for each idle stroke initial, constant acceleration motion followed by variable acceleration motion.

27. In combination with the reciprocating tyne bed of a printing press having a working stroke in one direction and an idle stroke in the opposite direction, mechanism for driving the bed, elements included in said mechanism which are in constant driving association with said bed and arranged to transmit to the bed its sequence of strokes, two alternately acting sets of roll-curve gears and coacting reversing members for imparting to the type bed, through the intermediary of said elements, its complete cycle of movement, one of said sets imparting to the type bed for each working stroke initial, constant acceleration motion followed by variable acceleration motion and then uniform motion,-and the other set of roll-curve gears imparting to the type bed for each idle stroke initial, constant acceleration motion followed by variable acceleration motion,

the maximum speed of the bed during each idle stroke being greater than the maximum speed of the bed during each working stroke.

28. The combination with a reciprocating machine element, of mechanism for driving it, including .a bed motion shaft constituting the only driving means applied to said element during its complete reciprocatory cycle, at least one driving shaft for imparting movement to said bed motion shaft, and means provided on each of said shafts and operating to impart to said element during one stroke thereof constant acceleration motion, variable acceleration motion and uniform motion in succession, whereby the variable acceleration motion joins the constant acceleration motion with the uniform motion.

29. In combination with the reciprocating type bed of a printing press, of mechanism for driving the bed including elements in constant driving association with said bed and arranged to transmit to the bed its sequence of strokes, and alternately acting driving and reversing means for imparting to the type bed, through the intermediary of said elements, its complete cycle of movement, said means being organized and operating to produce alternately, in one plane of action, variable acceleration, uniform motion and variable deceleration. 

